Search form

Providing the foundation for North Carolina’s emergency management planning

Harris Geiger-mode LiDAR Adds Value

January 10, 2018

North Carolina's FIMAN Flood Inundation Mapping Tool

As part of ongoing support to prime consultant ESP Associates and the State of North Carolina, Harris is enhancing and modernizing the knowledge base (physical features or topographic information) behind the state’s flood risk mapping tool, FIMAN. Emergency management personnel use FIMAN to understand the potential impacts of natural disasters and flooding and make plans to better prepare the state for emergencies.

North Carolina is physically a complex territory; its topography varies across three types of regions—the Mountains, the Piedmont, and the Coastal Plains—which represent more than 6,600 feet in elevation changes. Across the 53,819-square-mile state you can find national parks and pine tree forested areas, winding coastal zones, densely populated cities, and open rural areas. This variety of terrain poses mapping challenges. It would take years for field surveyors to map the features across the state.

Developments in light detecting and ranging (LiDAR) technology, where instruments take 3D topographic measurements from aircraft, have improved this process. However, there are still gaps in the information where traditional LiDAR just doesn’t give enough detail to help users fully understand the land surface terrain, and data acquisition across large areas can be time consuming.

Harris’ innovative Geiger-mode LiDAR collection technology is changing the way LiDAR elevation data is collected and raising the bar of standards. The system uses advanced sensors to more quickly gather large amounts of data that is of significantly higher resolution and produces a more homogeneous dataset, making it even more accurate and useful than traditional LiDAR. “It’s like comparing one of today’s fast, high-quality digital cameras with an older, lower-pixel cellphone camera that takes single-shot images,” explains Mark Romano, senior geospatial product manager. “From the aircraft, our sensor detects fine details as small as utility lines strung across cities, pavement markings on highways, and surface information through thick trees, while flying up to 10 times the altitude at three times the speed, and collecting areas greater than three miles in width.”

The higher-quality information gathered by Harris’ Geiger-mode LiDAR gives insight into very specific details that were previously only attainable by sending surveyors into remote locations or in congested downtown areas to collect. This new high-quality dataset keeps personnel out of harm’s way and frees them up for other tasks that contribute to organizational needs.

For ESP and, in turn, the State of North Carolina, Harris has collected more than 18,000 square miles of these detailed data points, accounting for about one third of the state’s territory. Special attention was given to one area of this project where the state required same-season data collection across a large area during its short “leaf-off” period. (“Leaf off” refers to when temperatures dip, and trees lose their leaves.) “As soon as the last leaves had fallen, our instrument was in the sky collecting data. We acquired 9,000 square miles of data to accomplish the state’s lofty goal,” said Romano.

High-resolution Harris LiDAR “point cloud” elevation data, a robust dataset of physical locations of land surface features, now feeds into North Carolina’s statewide flood risk mapping tool, providing more detailed data with consistent accuracy. This point cloud data measures natural surface features like rivers, trees, and hills, as well as man-made features like buildings and roadways, giving a precise GPS location to every point collected. The enhanced information is allowing the state to calculate potential flooding in parking lots, on roadways, and around buildings in residential neighborhoods. The state can now make plans to mitigate impacts that affect individuals directly—before the hazard strikes.

Although the primary purpose of North Carolina’s data collection effort is to enhance and modernize their statewide topography mapping network for emergency management, departments across the state are also turning to Harris LiDAR data to achieve more accurate and cost-efficient solutions. This approach enables the North Carolina Emergency Management Office to make a one-time data collection of across large areas and then apply it to multiple stakeholders’ projects, generating significant additional benefits.